Powdery mildew occurs in all kinds of vegetables such as pepper, tomato, cucumber and zucchini. In addition to the airborne flow and the transmission in the farming operation, pests on vegetables such as thrips, mites and whiteflies can also spread. In particular, in the summer of June to July, when the hot peppers and tomatoes are exposed, the powdery mildew is prone to epidemic if it is mixed with high temperature and the weather is hot and hot. If the planting density is too large, the field will be closed; the application of nitrogen Fertilizer will be excessive; if the irrigation is too much or the water accumulation after the rain cannot be eliminated in time; the continuous operation of the solanaceous vegetables and the large amount of soil bacteria are beneficial to the occurrence of powdery mildew.
Prevention
1. Strengthening cultivation and management of peppers and tomatoes is best not to be continuous with solanaceous fruits and melons. It is recommended to rotate with onions and garlic vegetables. Reasonable close planting to avoid excessive cultivation density. Apply sufficient fermented organic fertilizer, increase phosphorus and potassium fertilizer, and improve the disease resistance of the plant.
2. Remove the old leaves and diseased leaves in the lower part of the plant in time, remove the leaves caused by powdery mildew, and reduce the source of reinfection.
3. In the initial stage of drug control, 40% fluorosilazyl emulsifiable concentrate 8000 times solution, or 10% phenyl ether·cyclocycline water dispersible granule 1000 times solution, or 25% azoxystrobin suspension 1000 times solution, or 12.5% ​​nitrile emulsifiable concentrate 1500 times solution, or 30% fluconazole wettable powder 2500 times solution, or 25% tebuconazole water agent 2000 times solution. In addition, 65% methylsulfate-methylcarbamate wettable powder 800 times solution, or 50% sulfur suspension agent 300 times solution, or 25% propiconazole emulsion 3000 times solution may be used. Once every 7-10 days, 2-3 times in a row.
Note: First, the prevention and control of powdery mildew must be early. When there are chlorotic yellow spots on the sporadic leaves in the lower part of the plant, it is necessary to spray a protective agent for prevention or prevention, or to prevent it according to the incidence of previous years. Commonly used preventive protective agents include sulfur suspending agent, chlorothalonil WP, thiophanate-methyl WP and poly-mycin-resistant water. It is necessary to control powdery mildew in the spotting stage. The second is to pay attention to the rotation of alternating drugs to prevent the emergence of resistance to bacteria. Third, when using triazole fungicides such as flusilazole, it is necessary to strictly use the drug concentration, and must not use too much drug to avoid phytotoxicity.
Phytophthora capsici control technology
Some farmers' friends reflected that the base of the stalks of the open field became black and all died within a few days. What is going on? How to prevent it?
This is a typical Phytophthora capsici, which is an important disease in the growth phase of peppers. In the case of open field, the incidence is particularly serious.
First, the symptoms
Phytophthora capsici is also known as black smut. In pepper cultivation, it mainly damages the base of the stem, the diseased part collapses, the base of the stem becomes black and sag, and the plant wilts and dies within two or three days. In the case of rainy, it is often in the stalk. The fork produces water-stained dark brown to dark brown lesions, which expand upward from the stem section, and the diseased part is easily broken. When the humidity is high, there is a white powdery mildew layer on the surface of the lesion. The disease can also damage the fruits and leaves, and the leaves start from the leaf margin, producing nearly round or irregular water-stained lesions, and the lesions rapidly expand to the whole leaf rot or dry; the fruit is mostly from the pedicle, resulting in Water-stained indeterminate lesions, rapidly browning and soft rot, white and sparse mildew layers on the surface of the diseased parts of the leaves and fruits (ie, spore sacs and cysts of the pathogens), the disease becomes brown and dead, but not Fall off.
Second, the pathogen and disease conditions
The pathogen is the Phytophthora capsici fungus. The pathogens overwinter with oospores and chlamydospores in the soil with the diseased residues, which became the main source of infection in the coming year. Gansu seeds generally do not carry bacteria. After the wintering, the pathogens are splashed by the irrigation water or rainwater to the base of the stem, and the sporangia produced by the disease department is repeatedly infested by rainwater and watering.
The pathogen prefers high temperature and high humidity. When the temperature in the field is 25-30 °C, the relative humidity is higher than 85%, it is easy to be popular; when the temperature is suitable, as long as the water film around the stem and the leaves exist for 4-6 hours, Complete the infection and complete the infection cycle in 2-3 days.
Therefore, the disease is fast and prone to devastating losses. Generally, the land in the field or the poorly ventilated and light-transparent land in the field is seriously ill; it is not drained in time after the rain and is prone to prevalence.
Third, prevention and treatment measures
1, ridge cultivation, reasonable close planting. Pepper is a semi-arid deep-root crop that must be ridged and cultivated at a height of about 25 cm. Pepper irrigation must be shallow irrigation, and irrigation should not be applied to the ridge at any time.
2. Do a good job in pastoral hygiene, remove the sick body in time, and bring it to the field for centralized treatment.
3. Chemical control. In the early stage of the disease, 72.2% Plex water agent or 72% cream urea·manganese zinc 500-600 times, 98% carbendazim wettable powder 2000 times, 70% B. manganese wettable powder 1000 times, 58% metalaxyl can be used. Mn-Zn wettable powder 500 times or 64% anti-virus 矾 wettable powder 400-500 times with spray irrigation, each plant should be more than 150 ml, 7-10 days, 5-10 days in severe cases.
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